I just found out something that might be relevant:
I set up that Yubikey BIO as a passkey with encryption for two accounts (I have one for my personal passwords and another one that I use for work).
I can see the two FIDO resident credentials on the Yubikey.
The first one that I set up (my personal one) logs in with passkey to a locked vault.
The second one (that I set up for my work account after having set it for my personal account) decrypts the vault correctly.